The present invention relates to a method of and an apparatus for executing diagnostic testing of a ROM (Read Only Memory) assembled in a microcomputer used for controlling various kinds of electronic controllers of, for example, vehicles such as passenger cars and other industrial cars.
Heretofore, in the controlling microcomputers accommodated in various kinds of electronic controllers incorporated in car engines and transmissions of vehicles, diagnostic testing of the ROM assembled in the controlling microcomputer is carried out by the CPU (Central Processing Unit) of the same controlling microcomputers according to a testing program preliminary stored in the ROM to conduct diagnostic testing of any troubles, e.g., data volatilization, and damage, which might occur to the ROM. In this regard, Japanese Laid-open Patent Publications Nos. 2000-123594 and 2000-66963 should be referred to.
The diagnostic testing of the ROM is carried out in such a manner that the computation of the sum/parity is conducted in respect to the entire memory region of the ROM to compare the result of the computation with the sum/parity (expectation) that is preliminarily computed and stored within the ROM. When the comparison reveals that there is some discrepancy therebetween, it is notified that the ROM has some trouble rendering the ROM to be no good (NG) due to some trouble, and in turn the fail-safe process is executed.
On the other hand, with a controller for a vehicle, such as an electric controller for the throttle valve, which provides a direct affect on the maneuverability of the vehicle, it is absolutely necessary for detecting any ROM trouble during driving operation of it engine. Nevertheless, the diagnostic testing of the ROM trouble takes a rather long time, and therefore, the testing of the ROM trouble during driving operation of the engine might some adverse affect on the engine controlling function during the diagnostic testing.
Therefore, according to the technique disclosed in the above-mentioned Japanese Laid-open Patent Publication No. 2000-66963, the diagnostic testing of the ROM over the entire storing region thereof is continuously conducted at a high speed either before the start of the vehicle engine or at the moment of stopping of the vehicle engine on one hand, and on the other hand, a low speed testing of the ROM is intermittently conducted by interruption at a predetermined time cycle with each of the separated storing region of the ROM.
Nevertheless, as described above, the diagnostic testing of the ROM is conducted so as to detect any trouble within the ROM by using the testing program stored itself. Thus, if the storing region of the ROM, in which the diagnostic program is pre-stored, is involved in any trouble, such an unfavorable situation occurs in that the diagnostic program itself might not correctly function causing a lack of reliability in diagnostic testing of the ROM.
Further, for are purpose of implementing a constant testing of the ROM, if diagnostic testing of the ROM is intermittently carried out with each of the separated regions thereof by interruption at a predetermined time cycle during the engine operation, it takes a long time for carrying out the diagnostic testing of the ROM (complete testing of the ROM by calculating the parity of the entire storing regions requires approximately 10 minutes). Therefore, if any trouble occurs in a portion of the ROM, which might result in a fatal defect of the entire ROM function, it is difficult to quickly detect such trouble of the ROM to thereby immediately diagnose and recover the trouble.
Therefore, an object of the present invention is to provide an improved technique for carrying out diagnostic testing of a ROM, i.e., a ROM not exclusively but preferably incorporated in a controlling microcomputer used in a vehicle-incorporated electronic controller, in which technique a redundant diagnostic testing program using first and second diagnostic testing programs is employed for executing the diagnostic testing of a ROM by enabling it to surely detect any trouble in any part of the storing region of the ROM storing therein one of the first and second diagnostic programs by the other diagnostic program stored in a different storing region of the, ROM to thusly enhance a reliability of diagnostic testing of the ROM compared with the above-described existing testing technique of a ROM.
Another object of the present invention is to provide an improved technique for carrying out a high speed diagnostic testing of a ROM, in which while one of the first and second diagnostic programs of the redundant diagnostic program is employed for implementing the diagnostic testing of the entire storing region of the ROM, the other one is employed for quickly implementing the effective diagnostic resting of a limited storing region of the ROM.
A further object of the present invention is to provide an apparatus for achieving the abovementioned respective objects.
A still further object of the present invention is to provide a method of carrying out the diagnostic testing of a ROM, which realizes the above-mentioned improved techniques.
In accordance with one aspect of the present invention, there is provided an apparatus for executing a diagnostic testing of a ROM to diagnose whether or not any trouble exists in the ROM, which comprises:
predetermined first and second diagnostic testing programs for the ROM stored in one and the other separate regions of a storing region of the ROM; and
a processing unit for diagnosing the ROM on the basis of the predetermined first and second diagnostic testing programs,
wherein the processing unit works to:
execute the diagnostic testing of at least the one region of the storing region that stores the second diagnostic testing program by the first diagnostic testing program; and,
execute the diagnostic testing of at least the other region of the storing region that stores the first diagnostic testing program by the second diagnostic testing program.
In accordance with another aspect of the present invention, there is provided a vehicle-mounted diagnostic testing apparatus for executing a diagnostic testing of a ROM by the use of a central processing unit (CPU) to diagnose whether or not any trouble exists in the ROM, on the basis of a diagnostic testing program,
wherein the ROM preliminarily stores first and second diagnostic testing programs in different storing regions thereof, respectively; and initially stores at east either one of a control program and data to be used for controlling an electrically-controlled throttle valve of a vehicle-engine in one of the different storing regions that stores the second diagnostic testing program; and
wherein the CPU:
executes diagnostic testing of at least the one storing region that stores the second diagnostic testing program, on the basis of the first diagnostic testing program;
further executes diagnostic testing of at least the other storing region that stores the first diagnostic testing program, on the basis of the second diagnostic program; and
turns a power source of the electronically-controlled throttle valve off when the result of the diagnostic testing indicates that any trouble exists in the ROM.
In accordance with a further aspect of the present invention, there is provided a method of executing a diagnostic testing of a ROM on the basis of a diagnostic testing program for the ROM to diagnose whether or not any trouble exists in the ROM, comprises:
storing predetermined first and second diagnostic testing programs for the ROM in separate storing regions of the ROM, respectively;
working the first diagnostic testing program to execute diagnostic testing of at least a storing region of the ROM that stores therein the second diagnostic testing program; and,
working the second diagnostic testing program to execute diagnostic testing of at least a storing region of the ROM that stores them the first diagnostic program.
The above and other objects, features, and advantages of the present invention will be made more apparent by way of the following description of preferred embodiments with reference to the accompanying drawings.